Performance of primary students in mathematics among the countries participating in TIMSS is different. The purpose of this study is to compare the math curriculum of Iran with the five countries which were the pioneers in TIMSS 2015 (Singapore, Hong Kong, South Korea, Taiwan, and Japan). The research method was comparative and the statistical population consisted of all math books of the fourth grade in Iran and the leading countries. The findings showed that some elements are similar among the countries, such as the concepts of numbers, calculation, measurement, and geometry. However, the studied curricula are different from each other, regarding skill of math problem solving, analysis and application of mathematical topics, interesting statistics and algebra topics, and positive attitude to math learning, so that in Iran these areas have been somewhat neglected. At the end, some suggestions were offered based on the findings.